FIG. 1 illustrates a view showing links in a data transmission system using relays. The data transmission system includes a base station 110, relays 120 and 150, a macro terminal 130, and a relay terminal 140. The macro terminal transmits or receives data to or from the base station 110 through direct connection with the base station 110. The relay terminal directly connects with the relay 120.
The relay terminal 140 transmits data to the relay 120. The relay 120 forwards the received data to the base station 110. In addition, the base station 110 transmits the data to the relay 120 and, accordingly, the relay 120 transmits the received data to the relay terminal 140.
The base station 110, the relays 120 and 150, and the terminals 130 and 140 may transmit and receive data using a wireless resource. Depending on embodiments, a frequency range, a time slot, and the like may be used as the wireless resource.
The data transmission system properly allocates the wireless resources to uplinks and downlinks between the base station 110 and the relay 120, uplinks and downlinks between the relay 120 and the relay terminal 140, and uplinks and downlinks between the base station 110 and the macro terminal 130. The data transmission system transmits data using the allocated wireless resources.
FIG. 2 illustrates a drawing showing the structure of a data frame in a case where data transmission is performed by dividing frequency resources.
Part (a) of FIG. 2 shows the structure of the data frame that a base station transmits to a relay. The data frame 210 may include a control signal region 211, and data regions 212, 213, and 214.
A horizontal axis of the data frame denotes elapse of time while a vertical axis denotes a frequency range.
The control signal region 211 may transmit control signals corresponding to a reference signal (RS), a physical control format indicator channel (PCFICH), a physical downlink control channel (PDCCH), and a Physical H-ARQ Indicator Channel (PHICH). The control signal region 211 may include information on the data regions or wireless resources corresponding to the data regions. For example, the control signal region 211 may include information on a starting point and an ending point of each region, and information on a transmission frequency range of each region.
The data regions 212, 213, and 214 may include data regions 212 and 213 in which data is transmitted to a plurality of relays and a data region 214 in which data is transmitted to a macro terminal. In the data region 214, transmission of the data to the macro terminal may be performed using a physical downlink shared channel (PDSCH).
Part (b) of FIG. 2 illustrates a view showing the operation of a first relay with respect to each region of the data frame shown in part (a) of FIG. 2. In a region 221, the first relay transmits control signals for relay terminals.
In a region 223, the first relay receives data with respect to the first relay.
According to the embodiments of FIG. 2, the first relay performs no operation regarding the wireless resource for transmission of data related to a second relay and data related to the macro terminal in data regions 222 and 224, respectively. Thus, a waste of the wireless resource is induced.